Dispersive delay line with lamb wave propagation

ABSTRACT

Dispersive delay lines are disclosed. The dispersive delay line can include a piezoelectric substrate having a first interdigital transducer electrode on a first region of the piezoelectric substrate and a second interdigital transducer electrode on a second region of the piezoelectric substrate. The dispersive delay line is arranged such that an acoustic wave is configured to propagate from the first interdigital transducer electrode to the second interdigital transducer electrode though a third region of the piezoelectric substrate. An additional material positioned on the third region of the piezoelectric substrate can impact acoustic wave propagation velocity. Related radio frequency modules, wireless communications devices, and methods are disclosed.

CROSS REFERENCE TO PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 C.F.R. § 1.57.This application claims the benefit of priority of U.S. ProvisionalApplication No. 63/266,263, filed Dec. 30, 2021 and titled “DISPERSIVEDELAY LINE,” the disclosure of which is hereby incorporated by referencein its entirety and for all purposes. This application claims thebenefit of priority of U.S. Provisional Application No. 63/408,379,filed Sep. 20, 2022 and titled “DISPERSIVE DELAY LINE WITH PIEZOELECTRICSUBSTRATE,” the disclosure of which is hereby incorporated by referencein its entirety and for all purposes. This application claims thebenefit of priority of U.S. Provisional Application No. 63/408,415,filed Sep. 20, 2022 and titled “DISPERSIVE DELAY LINE WITH PIEZOELECTRICSUBSTRATE AND LAMB WAVE PROPAGATION,” the disclosure of which is herebyincorporated by reference in its entirety and for all purposes. Thisapplication claims the benefit of priority of U.S. ProvisionalApplication No. 63/408,388, filed Sep. 20, 2022 and titled “DISPERSIVEDELAY LINE WITH LAMB WAVE PROPAGATION,” the disclosure of which ishereby incorporated by reference in its entirety and for all purposes.

BACKGROUND Technical Field

Embodiments of this disclosure relate to delay lines. More specifically,embodiments disclosed herein relate to dispersive delay lines with Lambwave propagation.

Description of Related Technology

Delay lines including acoustic wave devices can be implemented in radiofrequency electronic systems. For instance, a radio frequency front endof a mobile phone can include one or more delay lines that includeacoustic wave devices. A delay line can include interdigital transducerelectrodes on a piezoelectric substrate. Example delay lines includeLamb wave delay lines and Rayleigh delay lines.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is a dispersive delay line that includes apiezoelectric substrate, a first interdigital transducer electrode, anda second interdigital transducer electrode. The piezoelectric substrateincludes a first region, a second region, and a third region. The firstinterdigital transducer electrode is on the first region of thepiezoelectric substrate. The second interdigital transducer electrode ison the second region of the piezoelectric substrate. The dispersivedelay line is arranged such that a Lamb wave is configured to propagatefrom the first interdigital transducer electrode to the secondinterdigital transducer electrode though the third region of thepiezoelectric substrate with a group delay that depends on frequency.

The Lamb wave can have a wavelength of k, and the third region of thepiezoelectric substrate can have a thickness that is less than 0.5λ. Thethird region of the piezoelectric substrate can have a thickness that isgreater than a thicknesses of the first region and that is greater thana thickness of the second region.

The group delay can have linear relationship with frequency. The groupdelay can have a non-linear relationship with frequency.

The piezoelectric substrate can have stepped heights in the thirdregion.

The dispersive delay line can include additional material on the thirdregion of the piezoelectric substrate, where the additional material isconfigured to adjust acoustic wave propagation in the third region.

The dispersive delay line can have a passband bandwidth in a range from0.5 gigahertz to 2 gigahertz. The dispersive delay line can have apassband bandwidth of more than 1 gigahertz.

The dispersive delay line can have a group delay in a range from 20nanoseconds to 100 nanoseconds. The dispersive delay line can have agroup delay in a range from 25 nanoseconds to 50 nanoseconds.

The dispersive delay line can have an operating frequency in range from5 gigahertz to 10 gigahertz. The dispersive delay line can have anoperating frequency of more than 10 gigahertz. The dispersive delay linecan have an operating frequency in Frequency Range 2 defined by a NewRadio standard.

The piezoelectric substrate can include aluminum nitride. The Lamb wavecan be a lowest order symmetric mode Lamb wave.

Another aspect of this disclosure is a dispersive delay line thatincludes a piezoelectric substrate, a first interdigital transducerelectrode, and a second interdigital transducer electrode. Thepiezoelectric substrate includes a first region, a second region, and athird region. The first interdigital transducer electrode is on thefirst region of the piezoelectric substrate. The second interdigitaltransducer electrode is on the second region of the piezoelectricsubstrate. The dispersive delay line is arranged such that a Lamb wavehaving a wavelength of λ is configured to propagate from the firstinterdigital transducer electrode to the second interdigital transducerelectrode though the third region of the piezoelectric substrate. Thethird region of the piezoelectric substrate has a thickness that is lessthan 0.5λ and that is greater than a thickness of the first region ofthe piezoelectric substrate.

The piezoelectric substrate can include aluminum nitride. The Lamb wavecan be a lowest order symmetric mode Lamb wave.

The dispersive delay line can have a passband of more than 0.5gigahertz. The passband can be less than 2 gigahertz. The dispersivedelay line can have a passband of more than 1 gigahertz.

The dispersive delay line can have a group delay in a range from 25nanoseconds to 50 nanoseconds. The dispersive delay line can have agroup delay in a range from 20 nanoseconds to 100 nanoseconds. Thedispersive delay line can have a group delay in a range from 20nanoseconds to 150 nanoseconds.

The dispersive delay line can have an operating frequency in range from5 gigahertz to 10 gigahertz. The dispersive delay line can have anoperating frequency of more than 10 gigahertz. The dispersive delay linecan have an operating frequency in Frequency Range 2 defined by a NewRadio standard.

The dispersive delay line can include additional material positioned onat least one of a top surface or a bottom surface of the piezoelectricsubstrate in the third region. The additional material can include atleast one of silicon dioxide, gallium nitride, or silicon nitride.

The thickness of the third region of the piezoelectric substrate candecrease adjacent to the first region and adjacent to the second region.

A first thickness of the piezoelectric substrate adjacent a first end ofthe third region proximal to the first interdigital transducer can beless than 0.5λ, and a second thickness of the piezoelectric substrateadjacent a second end of the third region proximal to the secondinterdigital transducer electrode can be less than the first thicknessof the piezoelectric substrate.

The thickness of the piezoelectric substrate in the third region can bescaled linearly between the first thickness and the second thickness.The thickness of the piezoelectric substrate in the third region can bescaled non-linearly between the first thickness and the secondthickness.

A first thickness of the piezoelectric substrate adjacent a first end ofthe third region proximal to the first interdigital transducer can beless than 0.5λ, a second thickness of the piezoelectric substrateadjacent a second end of the third region proximal to the secondinterdigital transducer electrode can be less than or equal to the firstthickness of the piezoelectric substrate, and a third thickness of thepiezoelectric substrate at a narrowed portion of the piezoelectricsubstrate located between the first and second ends in the third regioncan be less than the second thickness. The third thickness of thepiezoelectric substrate can be greater than or equal to a thickness ofthe piezoelectric substrate in the first region.

Another aspect of this disclosure is a dispersive delay line thatincludes a piezoelectric substrate, a first interdigital transducerelectrode, a second interdigital transducer electrode, and additionalmaterial. The piezoelectric substrate includes a first region, a secondregion, and a third region. The first interdigital transducer electrodeis on the first region of the piezoelectric substrate. The secondinterdigital transducer electrode is on the second region of thepiezoelectric substrate. The additional material is on the third regionof the piezoelectric substrate. The additional material is configured toadjust acoustic wave propagation velocity in the third region of thepiezoelectric substrate. The dispersive delay line is arranged such thata Lamb wave of wavelength λ is configured to propagate from the firstinterdigital transducer electrode to the second interdigital transducerelectrode though the third region of the piezoelectric substrate with agroup delay that depends on frequency.

The additional material can be positioned on both a top surface and abottom surface of the piezoelectric substrate in the third region.

The additional material can include silicon dioxide. The additionalmaterial can include gallium nitride. The additional material caninclude silicon nitride.

The piezoelectric substrate can have a substantially constant thicknessin the first region, the second region, and the third region.

The group delay can have a linear relationship with frequency. The groupdelay can have a non-linear relationship with frequency.

The dispersive delay line can have a passband bandwidth in a range from0.5 gigahertz to 2 gigahertz. The dispersive delay line can have apassband bandwidth of more than 1 gigahertz.

The group delay can be in a range from 20 nanoseconds to 100nanoseconds.

The dispersive delay line can have an operating frequency in range from5 gigahertz to 10 gigahertz. The dispersive delay line can have anoperating frequency in Frequency Range 2 defined by a New Radiostandard.

The piezoelectric substrate can include aluminum nitride. The Lamb wavecan be a lowest order symmetric mode Lamb wave.

Another aspect of this disclosure is a radio frequency module thatincludes a dispersive delay line in accordance with any suitableprinciples and advantages disclosed herein, radio frequency circuitrycoupled to the dispersive delay line, and a packaging structureenclosing the dispersive delay line and the radio frequency circuitry.

Another aspect of this disclosure is a wireless communication deviceincluding a that includes a dispersive delay line in accordance with anysuitable principles and advantages disclosed herein and an antenna incommunication with the dispersive delay line.

Another aspect of this disclosure is a method of radio frequency signalprocessing. The method includes providing a dispersive delay line inaccordance with any suitable principles and advantages disclosed herein,and frequency modulating a radio frequency signal with the dispersivedelay line.

Another aspect of this disclosure is a method of radio frequency signalprocessing. The method includes providing a dispersive delay line inaccordance with any suitable principles and advantages disclosed herein,and frequency demodulating a radio frequency signal with the dispersivedelay line.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the innovations have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment. Thus, theinnovations may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

The present disclosure relates to U.S. Patent Application No. ______[Attorney Docket SKYWRKS.1191A1], titled “DISPERSIVE DELAY LINE WITHPIEZOELECTRIC SUBSTRATE,” filed on even date herewith, the entiredisclosure of which is hereby incorporated by reference herein. Thepresent disclosure relates to U.S. Patent Application No. ______[Attorney Docket SKYWRKS.1191A2], titled “DISPERSIVE DELAY LINE WITHPIEZOELECTRIC SUBSTRATE AND LAMB WAVE PROPAGATION,” filed on even dateherewith, the entire disclosure of which is hereby incorporated byreference herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIG. 1A illustrates a schematic cross-sectional diagram of a dispersivedelay line according to an embodiment.

FIG. 1B illustrates a schematic cross-sectional diagram of a dispersivedelay line according to another embodiment.

FIG. 1C illustrates a schematic cross-sectional diagram of a dispersivedelay line according to another embodiment.

FIG. 1D illustrates a schematic cross-sectional diagram of a dispersivedelay line according to yet another embodiment.

FIG. 1E illustrates a schematic cross-sectional diagram of a dispersivedelay line according to an additional embodiment.

FIG. 2A illustrates a schematic cross-sectional diagram of a part of adispersive delay line according to an embodiment.

FIG. 2B is a graph that illustrates a non-linearized group delay for adispersive delay line according embodiments.

FIG. 2C is a graph that illustrates a linearized group delay for adispersive delay line according embodiments.

FIGS. 3A and 3B are graphs associated with simulations of a dispersivedelay line according to an embodiment and a conventional delay line.

FIG. 4 illustrates a S0 Lamb wave mode at a boundary between a wavesource and the waveguide in a schematic cross section corresponding toFIG. 2 .

FIG. 5 is a graph that shows dispersion in a delay line with a waveguidethat is thicker than a thin plate and no dispersion when the waveguideis the same thickness or thinner than the thickness of a substrateacross an interdigital transducer (IDT) electrode.

FIG. 6 is schematic block diagram of an illustrative packaged moduleaccording to an embodiment.

FIG. 7 is a schematic diagram of one embodiment of a mobile device.

FIG. 8 is a schematic diagram of one example of a communication network.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following description of certain embodiments presents variousdescriptions of specific embodiments. However, the innovations describedherein can be embodied in a multitude of different ways, for example, asdefined and covered by the claims. In this description, reference ismade to the drawings where like reference numerals can indicateidentical or functionally similar elements. It will be understood thatelements illustrated in the figures are not necessarily drawn to scale.Moreover, it will be understood that certain embodiments can includemore elements than illustrated in a drawing and/or a subset of theelements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings.

A dispersive delay line (DDL) can be utilized for passive formation andcompression of frequency-modulated (FM) signals. In certainapplications, the FM signals can have a frequency in Frequency Range 1(RF1) as defined by a New Radio (NR) standard. A DLL can enable settingboth linear and non-linear frequency modulation. A DLL can providepositive or negative slopes of the dispersion characteristic. DLLsdisclosed herein can achieve high dispersion of group velocity of a Lambwave. A time delay of about 100 nanoseconds can be achieved with lowacoustic damping with a DLL according to an embodiment.

A DLL can be used to compress an FM signal. The compression coefficient,which can be a product of the duration of the FM signal by the passband,can reach 100. A DLL can also modulate and/or demodulate an FM signal.

A DLL can include a first interdigital transducer electrode and a secondinterdigital transducer electrode on a piezoelectric substrate. Incertain embodiments, one or more thicker parts of the piezoelectricsubstrate between the parts of the piezoelectric substrate on which thefirst and second interdigital transducer electrodes are positioned canfunction as a waveguide for a Lamb wave having a wavelength of λ andpropagating between the first and second interdigital transducerelectrodes. The thicker part of the piezoelectric substrate can have athickness that is of less than 0.5λ and that is greater than the partsof the piezoelectric substrate under the first and second interdigitaltransducer electrodes. The piezoelectric substrate can be an aluminumnitride (AlN) piezoelectric substrate. The Lamb wave can be a S0symmetrical mode Lamb wave. An S0 symmetrical mode Lamb wave is a lowestorder symmetric mode Lamb wave. The dispersive delay line providesdispersion over a passband. With the dispersive delay line, group delayis adjusted over frequency. The passband can be relatively wide, such asat least about 1 gigahertz (GHz).

DLLs are disclosed with a velocity dispersed thin plate waveguide athigh order S0 symmetrical Lamb wave mode. DLLs disclosed herein canachieve a high delay time. This can be a result of the relatively lowervelocity of the Lamb wave in solids. DLLs disclosed herein can have ahigh working frequency suitable for Fifth Generation (5G) NRapplications, such as applications over 10 GHz. DLLs disclosed hereincan have a wide frequency range, such as a frequency range of over 1GHz. DLLs disclosed herein can have low losses. This can result fromrelatively low acoustical dumping in a thin plate Lamb wave device. DLLsdisclosed herein can have a controllable dispersion characteristic. Thedispersion characteristic can be controllable via thickness of thewaveguide of the DLL.

Embodiments of DLLs will now be discussed. A DLL can be implemented inaccordance with any suitable principles and advantages of theembodiments of the DLLs disclosed herein.

FIG. 1A illustrates a schematic cross-sectional diagram of a DLL 10Aaccording to an embodiment. The DLL 10A has a velocity dispersed thinplate waveguide at zero order S0 symmetrical Lamb wave regime. Thedispersion achievable is the difference in group velocity of the S0 Lambwave in the thin plate with different thicknesses of the waveguide. TheDLL 10A can adjust group delay for different frequencies in itspassband. As will be discussed herein with reference to FIGS. 2B and 2C,a DLL can have a nonlinear group delay or a linearized group delay oversome or all of the passband. For example, the DLL 10A can have anonlinear group delay in the passband. The DLL 10A can have a relativelyhigh operating frequency. In certain applications, the operatingfrequency can be in a range from 5 GHz to 10 GHz, above 10 GHz, in arange from 10 GHz to 20 GHz, above 20 GHz, or in Frequency Range 2 (FR2)as defined by a NR standard.

As shown in FIG. 1A, the DLL 10A includes a piezoelectric substrate 12and a plurality of interdigital transducer (IDT) electrodes 14 and 16 onthe piezoelectric substrate 12. The piezoelectric substrate 12 can be analuminum nitride piezoelectric substrate or any other suitablepiezoelectric substrate. Aluminum nitride piezoelectric substrates canbe useful in certain high frequency applications. The piezoelectricsubstrate 12 can be a doped. For example, the piezoelectric substrate 12can be an aluminum nitride piezoelectric substrate doped with scandium.Accordingly, a piezoelectric substrate that includes aluminum nitridecan also include a dopant.

The piezoelectric substrate 12 has a thickness of H₁ in regions 12A and12B under the IDT electrodes 14 and 16, respectively. The regions 12Aand 12B of the piezoelectric substrate 12 under the IDT electrodes 14and 16 can be referred to as thin plate regions. The piezoelectricsubstrate 12 has a thickness H₂ in a region 12C between the thin plateregions 12A and 12B. The region 12C can function as a waveguide. Themajority of the region 12C can have the thickness H₂, and thickness inthe region 12C can decrease adjacent to the regions 12A and 12B. Forexample, as shown in FIG. 1A, thickness can linearly decrease from H₂ toH₁ in areas of the region 12B adjacent to the regions 12A and 12B. Insome other applications, the region 12C can have a substantiallyconstant thickness.

The IDT electrode 14 and the region 12A of the piezoelectric substrate12 are included in a Lamb wave element that can generate a Lamb wave.The IDT electrode 14 can excite a S0 zero order symmetrical Lamb wavehaving a wavelength of k. The S0 zero order symmetrical Lamb canpropagate through the waveguide to the IDT electrode 16. The thicknessH₁ of the thin plate regions 12A and 12B can be in a range from 0.1λ to0.5λ, for example. For instance, the thickness H₁ can be 0.3λ in certainapplications. As illustrated in FIG. 1A, the thin plate regions 12A and12B can have the same thickness H₁. The thickness H₂ of thepiezoelectric substrate 12 in region 12C is greater than the thicknessH₁ in regions 12A and 12B in certain applications. In certainembodiments, the thickness H₂ can be less than 0.5λ. The IDT electrodes14 and 16 are spaced apart by a distance of L_(SP). As will be discussedin greater detail herein, a profile of one or more waveguide regions(such as, the region 12C) can have a varied thickness and/or a shorterlength to reduce losses incurred by the DLL 10A for Lamb waves ofvarious wavelengths.

The bottom of FIG. 1A shows a group delay velocity Vg distribution forthe different regions of the piezoelectric substrate 12. The group delayvelocity Vg is smaller in the waveguide region 12C than in the regions12A and 12B. For example, the group delay velocity Vg can be less than10 km/s in the region 12C and greater than 10 km/s in the regions 12Aand 12B. The group delay time can depend on the length L_(SP) betweenthe IDT electrodes 14 and 16, and the length and physical profile of thewaveguide region 12C. In certain applications, the group delay can be ina range from 25 nanoseconds (ns) to 50 ns, in a range from 20 ns to 100ns, or in a range from 20 ns to 150 ns.

The piezoelectric substrate 12 can be manufactured in a variety ofdifferent ways. In certain instances, a piezoelectric substrate ofthickness H₂ can be removed (e.g., etched) in regions 12A and 12B toreduce to thickness H₁ in those regions. In some instances,piezoelectric material can be deposited (e.g., sputtered) over region12C of a piezoelectric substrate of thickness H₁ to increase thethickness in region 12C to H₂. The piezoelectric substrate can bemanufactured by stepped sputtering and etching in various applications.

In another embodiment, for example as shown in FIG. 1B, a DLL 10B canhave a piezoelectric substrate 12 of consistent thickness H₁ throughout.In FIG. 1B, the piezoelectric substrate 12 has a substantially constantthickness. A first layer 18A and a second layer 18B of additionalmaterial can be included on opposing sides of the piezoelectricsubstrate 12 in the waveguide region 12C′. In some other applications,additional material can be included on one side of the piezoelectricsubstrate 12 in the waveguide region 12C′. The additional material caninclude, for example, one or more of silicon dioxide, gallium nitride,silicon nitride, or any other suitable material. The additional materialcan provide different acoustic impedance of the waveguide and alter thewave propagation velocity of the Lamb waves compared to thepiezoelectric layer without the additional material present. Thecomposition and dimensions of the layers 18A and 18B of additionalmaterial can be selected to achieve one or more of lower losses, longergroup delays, enhanced bandwidth, or improved thermal stability of theDDL 10B.

As illustrated, the layers 18A and 18B of additional material can havesubstantially constant thickness. In some other applications, one ormore layers of additional material can have any suitable non-constantthickness. In the DLL 10B, the combined thickness of the waveguideregion 12C′ of the piezoelectric substrate 12 and the layers ofadditional material can be less than 0.5λ and greater than the thicknessH₁ in the region 12A.

Although additional material to adjust wave propagation velocity in awaveguide region is shown with a piezoelectric substrate 12 withsubstantially constant thickness in FIG. 1B, such additional materialcan be included in a DLL with a wave guide region of a piezoelectricsubstrate having varied thickness. For example, additional material canbe included on some or all of at least one side of the piezoelectricsubstrate in a waveguide region of any of the DLLs of FIG. 1A, FIG. 1C,FIG. 1D, or FIG. 1E. Additional material can be included in combinationwith DLLs including any suitable combination of features disclosedherein.

FIG. 1C illustrates a schematic cross-sectional diagram of a DLL 10Caccording to another embodiment. The DLL 10C has a velocity dispersedthin plate waveguide at zero order S0 symmetrical Lamb wave regime. Likethe DLL 10A of FIG. 1A, dispersion achievable by the DLL 10C is thedifference in group velocity of the S0 Lamb wave in the piezoelectricsubstrate 12 between the thin plate regions 12A and 12B and a waveguideregion 12C″. The DLL 10C can adjust group delay for differentfrequencies in its passband, the passband being at least partiallydetermined by the physical profile of the waveguide region 12C″.

As will be discussed herein with reference to FIG. 2C, the DLL 10C canhave a linearized group delay over some or all of the passband. The DLL10C can have a relatively high operating frequency, in some cases higherthan that of the DLLL 10A of FIG. 1A. For Lamb waves in a particularrange of frequencies (such as, frequencies above approximately 5 GHz),the DLL 10C can have improved performance and reduced signal losses. Incertain applications, the operating frequency can be in a range from 5GHz to 10 GHz, above 10 GHz, in a range from 10 GHz to 20 GHz, above 20GHz, or in FR2 as defined by a NR standard.

The piezoelectric substrate 12 of the DLL 10C can be an aluminum nitridepiezoelectric substrate or any other suitable piezoelectric substrate.The piezoelectric substrate 12 has a thickness of H₁ in the thin plateregions 12A and 12B underneath the IDT electrodes 14 and 16,respectively. In the centrally-located waveguide region 12C″, thepiezoelectric substrate 12 has a varying thickness that decreasesbetween the thin plate region 12A and the thin plate region 12B. In thewaveguide region 12C″, the piezoelectric substrate 12 has a firstthickness H_(2,1). proximal to the thin plate region 12A Proximal to thethin plate region 12B, the piezoelectric substrate 12 has a secondthickness H_(2,2), which is smaller than H_(2,1).

As shown by FIG. 1C, the profile of the piezoelectric substrate 12 inthe waveguide region 12C″ can scale linearly between the first thicknessH_(2,1) and the second thickness H_(2,2). In some other embodiments, theprofile of the piezoelectric substrate 12 may scale according to anysuitable non-linear tapering function (for example, exponentially orquadratically). In an additional embodiment, the second thicknessH_(2,2) can be equivalent to the thickness H₁ of the thin plate region12B, causing the waveguide region 12C″ to transition smoothly from thefirst thickness H_(2,1) into the thin plate region.

When excitation of a S0 zero order symmetrical Lamb wave by the IDTelectrode 14 occurs, the Lamb wave can propagate through the waveguideto the IDT electrode 16 in the DLL 10C. The first thickness H_(2,1) andthe second thickness H_(2,2) of the piezoelectric substrate 12 in thewaveguide region 12C″ are preferably greater than the thickness H₁ inregions 12A and 12B. In certain embodiments, the first thickness H_(2,1)and/or the second thickness H_(2,2) can be less than 0.5λ. The IDTelectrodes 14 and 16 are spaced apart from each other by a distance ofL_(SP). By scaling the profile of the piezoelectric substrate 12 in thewaveguide region 12C″, the group delay velocity Vg of the Lamb wave canbe gradually increased between the first end and the second end of thewaveguide region 12C″. For example, the group delay velocity Vg can beless than 10 km/s at the first end of the waveguide region 12C″, andgreater than 10 km/s approaching the second end in the waveguide regionand in the regions 12A and 12B. The group delay time can depend at leastin part on the length L_(SP) as well as the scaling and profile of thepiezoelectric substrate 12 in the waveguide region 12C″.

A DLL can include a stepped waveguide structure to achieve a particulargroup delay distribution along a passband. Example DLLs with steppedwaveguide structures will be discussed with reference to FIGS. 1D and1E.

FIG. 1D illustrates a schematic cross-sectional diagram of a DLL 10Daccording to another embodiment. The DLL 10D has a pair of velocitydispersed thin plate waveguides at zero order S0 symmetrical Lamb waveregime. Dispersion achievable by the DLL 10D is the difference in groupvelocity of the S0 Lamb wave in the piezoelectric substrate 12 betweenthe thin plate regions 12A and 12B and a pair of stepped waveguideregions 12C₁ and 12C₂. The DLL 10D can adjust group delay for differentfrequencies in its passband, the passband being at least partiallydetermined by the physical profile of the waveguide regions 12C₁ and12C₂.

The DLL 10D can have a relatively high operating frequency, in somecases higher than those of the embodiments of FIG. 1A or 1C. For Lambwaves in a particular range of frequencies (such as, frequencies aboveapproximately 5 GHz), the DLL 10D can have improved performance andreduced signal losses. In certain applications, the operating frequencycan be in a range from 5 GHz to 10 GHz, above 10 GHz, in a range from 10GHz to 20 GHz, above 20 GHz, or in FR2 as defined by a NR standard.

The piezoelectric substrate 12 of the DLL 10D can be an aluminum nitridepiezoelectric substrate or any suitable piezoelectric substrate. Thepiezoelectric substrate 12 has a thickness of H₁ in the thin plateregions 12A and 12B underneath the IDT electrodes 14 and 16,respectively. In this embodiment, the piezoelectric substrate 12 has athickness H₂ in the pair of stepped waveguide regions 12C₁ and 12C₂centrally located between the thin plate regions. In certainapplications, there can be three or more stepped waveguide regionslocated between the thin plate regions. As shown in FIG. 1D, thewaveguide regions 12C₁ and 12C₂ each have a length L_(C1) and L_(C2),respectively. The length L_(C1) is preferably greater than L_(C2), butin some cases the lengths can be equal. The waveguide regions 12C₁ and12C₂ are separated by a narrowed region 12D of length L_(D), where thepiezoelectric substrate 12 has the same or a similar thickness to H₁. Incertain embodiments, the piezoelectric substrate 12 can have anintermediate thickness in a range between H₁ and H₂ in narrowed region12D. The sum of the lengths L_(C1), L_(C2), and L_(D) is less than orequal to the distance L_(SP) between the IDT electrodes 14 and 16.

When excitation of a S0 zero order symmetrical Lamb wave by the IDTelectrode 14 occurs, the Lamb wave can propagate through the waveguidesto the IDT electrodes 16. In certain embodiments, the thickness H₂ canbe less than 0.5λ. The group delay velocity Vg of the Lamb wave can bereduced, increased, and reduced again by the waveguide regions 12C₁ and12C₂ and the narrowed region 12D to achieve a specific group delaydistribution over the pass band of the waveguides. The group delay timecan depend at least in part on the lengths L_(SP), L_(C1), L_(C2), andL_(D), as well as the profile of the piezoelectric substrate 12 in eachof the waveguide regions 12C₁ and 12C₂.

FIG. 1E illustrates a schematic cross-sectional diagram of a DLL 10Eaccording to an another embodiment. The piezoelectric substrate 12 has athickness of H₁ in the thin plate regions 12A and 12B underneath the IDTelectrodes 14 and 16, respectively. Compared to the DLL 10D of FIG. 1D,in this embodiment, the piezoelectric substrate 12 has a first thicknessH_(2,1) in a first one of a pair of complementary waveguide regions12F₁, and a second thickness H_(2,2) in a second one of the pair ofcomplementary waveguide regions 12F₂.

Both waveguide regions 12F₁ and 12F₂ are centrally located between thethin plate regions 12A and 12D. The waveguide regions 12F₁ and 12F₂ areseparated by a narrowed region 12G of length L_(G), where thepiezoelectric substrate 12 has the same or a similar thickness to H₁. Incertain embodiments, the piezoelectric substrate 12 can have anintermediate thickness in a range between H₁ and H_(2,2) in the narrowedregion 12G. In certain applications, there can be three or more distinctwaveguide regions 12F_(n) located between the thin plate regions, eachwaveguide region having a corresponding thickness H_(n) and separated bytwo or more narrowed regions 12G_(n-1).

When excitation of a S0 zero order symmetrical Lamb wave by the IDTelectrode 14 occurs, the Lamb wave can propagate through the waveguidesto the IDT electrode 16. In certain embodiments, the first thicknessH_(2,1) can be less than 0.5λ, and preferably greater than the secondthickness H_(2,2), causing a greater reduction in group delay velocityVg as a Lamb wave passes through the first waveguide region 12F₁. Thegroup delay velocity Vg of the Lamb wave can be reduced, increased, andreduced again by the waveguide regions 12F₁ and 12F₂ and the narrowedregion 12G. The lengths L_(SP), LH, L_(F2), and L_(G) of the variousregions of the piezoelectric substrate 12 can also be selected to adjustthe group delay time and characteristics (such as linearity) of the DLL10.

FIG. 2A illustrates a schematic cross-sectional diagram of a part of aDLL 20 according to an embodiment. In the DLL 20, region 12A of thepiezoelectric substrate has a thickness of 0.3λ and region 12C of thepiezoelectric substrate has thickness of greater than 0.3λ, such as0.4λ.

FIG. 2B is a graph that illustrates a non-linearized group delay for aDLL, such as the DLLs 10A and 20 of FIGS. 1A and 2A, respectively. InFIG. 2B, delay duration increases non-linearly with frequency. Between afirst passband frequency f₁ and a second passband frequency f₂, groupdelay duration rises substantially nonlinearly over some or all of thepassband. In certain embodiments, group delay can be linear for aspecific frequency range within the passband and nonlinear outside ofthe range. The group delay is said to be non-linearized because thephysical profile, length, and composition of the DLLs 10A and 20 havenot been configured to produce a substantially linear group delay.

FIG. 2C is a graph that illustrates a linearized group delay for a DLL,such as the DLL 10C of FIG. 1C. In FIG. 2C, delay duration increaseslinearly with frequency. Due to the decreasing thickness of thepiezoelectric substrate 12 over the waveguide region 12C″ in the DLL10C, the group delay duration for the DLL 10C rises substantiallylinearly between the first passband frequency f₁ and the second passbandfrequency f₂. In certain embodiments, group delay can be linear for aspecific frequency range within the passband and nonlinear outside ofthe range.

FIGS. 3A and 3B are graphs associated with simulations of the DLL 20 ofFIG. 2A and a conventional delay line. The simulated DLL 20 hadthickness H₁ of 0.3λ and thickness H₂ of 0.4λ. FIG. 3A is a graph oftransmittance and insertion loss parameters. FIG. 3A indicates apassband of about 1 GHz. FIG. 3B is a graph of group delay. FIG. 3Bindicates dispersion in the DLL 20 and no dispersion in the conventionaldelay line. In FIG. 3B, the group delay ranges from about 25 ns to about50 ns in the passband for the DLL 20. The change in group delay over thepassband for the DLL 20 indicates dispersion. The simulation indicates adelay time dispersion from 25 ns to 50 ns with a passband of about 1 GHzat an operating frequency of 8 GHz for the DLL 20. By contrast, there isno dispersion indicated in FIG. 3B for the conventional delay line asthe delay time is generally constant at about 25 ns.

FIG. 4 illustrates a S0 mode at a boundary between a wave source (IDTelectrode) and the waveguide in a schematic cross section correspondingto FIG. 2 . FIG. 4 can correspond to an operating frequency of 8 GHz.FIG. 4 indicates that there is relatively low distortion for the S0 Lambwave at the boundary of the Lamb wave element and the waveguide, wherethe Lamb wave element includes the IDT electrode 14 and the region 12Aof the piezoelectric substrate.

FIG. 5 is a graph that shows dispersion in a delay line with a waveguidethat is thicker than a thin plate and no significant dispersion when thewaveguide is the same thickness or thinner than the thin plate. Variousthicknesses H₂ of the waveguide for a delay line that is generallysimilar in structure to the DLL 10A of FIG. 1A were simulated. The threecurves in FIG. 5 correspond to the waveguide region 12C having thicknessH₂ of 0.16λ, 0.3λ, and 0.4λ with the thin plate region 12A, 12B havingthickness H₁ of 0.3λ in each of the simulations. FIG. 5 indicates nogroup delay dispersion for thickness H₂ that is less than (e.g., 0.16λ)or equal to (e.g., 0.3λ) thickness H₁. For a thickness H₂ (e.g., 0.4λ)that is greater than H₁, FIG. 5 indicates group delay dispersion.

FIG. 5 indicates that there can be dispersion when the waveguidethickness is greater than the thin plate thickness. When the thicknessH₂ is greater than H₁, Lamb wave group velocity dispersion is indicated.If waveguide thickness is great than 0.5λ, the Lamb wave shape canchanges due to relatively high losses that can occur at the boundarywith different acoustic impedance. Accordingly, the waveguide regionthickness H₂ can be (1) greater than the thin plate region thickness H₁and (2) less than 0.5λ for dispersion to occur in the DLL 10.

While FIG. 5 shows how thickness of a piezoelectric waveguide can impactdispersion, a DLL can alternatively or additionally be implemented withother structural features that can cause dispersion. For example,additional material (e.g., silicon dioxide, gallium nitride, siliconnitride) can be included on at least one side of the waveguide to alterthe wave propagation velocity. This can create group delay dispersion.

In addition, although FIG. 5 includes curves corresponding to constantthickness piezoelectric waveguides, a piezoelectric waveguide can haveany suitable profile to create a DLL. Example profiles include steppedregion (e.g., as shown in FIGS. 1D and 1E) and sloped or tapered regions(e.g., as shown in FIG. 1C).

DLLs disclosed herein can achieve a relatively high delay time, such asabout 50 ns. DLLs disclosed herein can be implemented in high frequencyapplications. DLLs disclosed herein are suitable for 5G applicationsand/or applications with a frequency over 10 GHz. DLLs disclosed hereincan be used in applications with frequencies of 20 GHz or higher. DLLscan be used for 5G applications in Frequency Range 2 (FR2). DLLsdisclosed herein can achieve a relatively wide frequency range, such aspassband over 0.5 GHz, over 1 GHz, in a range from 0.5 GHz to 2 GHz,etc. At the same time, there can be relatively low losses. This can bedue to low acoustical dumping in thin plate Lamb wave structures. Delaytime and dispersion characteristic can be controlled via propagationlength (L_(SP)) and thickness of the waveguide (H₂), respectively. Thepropagation length can adjust the delay time. The slope of thedispersion characteristic can be adjusted by changing waveguidethickness. In certain applications, the dispersion characteristic can belinearized through some or all of a passband of a dispersive delay line.

DLLs disclosed herein can be implemented in radio frequency modules.FIG. 6 is a schematic diagram of a radio frequency module 175 thatincludes an acoustic wave component 176 according to an embodiment. Theillustrated radio frequency module 175 includes the acoustic wavecomponent 176 and other circuitry 177. The acoustic wave component 176includes a dispersive delay line 178 implemented in accordance with anysuitable principles and advantages disclosed herein. The terminals 179Aand 179B can serve, for example, as an input contact and an outputcontact.

The acoustic wave component 176 and the other circuitry 177 are on acommon packaging substrate 180 in FIG. 6 . The packaging substrate 180can be a laminate substrate. The terminals 179A and 179B can beelectrically connected to contacts 181A and 181B, respectively, on thepackaging substrate 180 by way of electrical connectors 182A and 182B,respectively. The electrical connectors 182A and 182B can be bumps orwire bonds, for example. The other circuitry 177 can include anysuitable additional circuitry. For example, the other circuitry 177 caninclude one or more one or more power amplifiers, one or more radiofrequency switches, one or more filters, one or more low noiseamplifiers, other radio frequency circuitry, the like, or any suitablecombination thereof. Power amplifiers and low noise amplifiers areexamples of radio frequency amplifiers. The radio frequency module 175can include one or more packaging structures to, for example, provideprotection and/or facilitate easier handling of the radio frequencymodule 175. Such a packaging structure can include an overmold structureformed over the packaging substrate 180. The overmold structure canencapsulate some or all of the components of the radio frequency module175.

DLLs disclosed herein can be implemented in a variety of wirelesscommunication devices, such as mobile devices. Such mobile devices caninclude mobile phones, such as smart phones. The DLLs can be included inradio frequency circuitry of the wireless communication device, such ascircuitry of a radio frequency front end. FIG. 7 is a schematic diagramof one embodiment of a mobile device 390. The mobile device 390 includesa baseband system 391, a transceiver 392, a front end system 393,antennas 394, a power management system 395, a memory 396, a userinterface 397, and a battery 398. A DLL can be implemented in anysuitable transmit circuitry of the mobile device 390. A DLL can beimplemented in any suitable receive circuitry of the mobile device 390.For example, a delay line 406 of the front end system 393 can beimplemented in accordance with any suitable principles and advantagesdisclosed herein. A DLL can provide passive modulation. A DLL canprovide passive demodulation. A DLL can provide frequency compression.

The mobile device 390 can be used communicate using a wide variety ofcommunications technologies, including, but not limited to, secondgeneration (2G), third generation (3G), fourth generation (4G)(including LTE, LTE-Advanced, and LTE-Advanced Pro), fifth generation(5G) New Radio (NR), wireless local area network (WLAN) (for instance,WiFi), wireless personal area network (WPAN) (for instance, Bluetoothand ZigBee), WMAN (wireless metropolitan area network) (for instance,WiMax), Global Positioning System (GPS) technologies, or any suitablecombination thereof.

The transceiver 392 generates RF signals for transmission and processesincoming RF signals received from the antennas 394. It will beunderstood that various functionalities associated with the transmissionand receiving of RF signals can be achieved by one or more componentsthat are collectively represented in FIG. 7 as the transceiver 392. Inone example, separate components (for instance, separate circuits ordies) can be provided for handling certain types of RF signals.

The front end system 393 aids in conditioning signals transmitted toand/or received from the antennas 394. In the illustrated embodiment,the front end system 393 includes antenna tuning circuitry 400, poweramplifiers (PAs) 401, low noise amplifiers (LNAs) 402, filters 403,switches 404, signal splitting/combining circuitry 405, and one or moredelay lines 406. However, other implementations are possible.

The front end system 393 can provide a number of functionalities,including, but not limited to, amplifying signals for transmission,amplifying received signals, filtering signals, switching betweendifferent bands, switching between different power modes, switchingbetween transmission and receiving modes, duplexing of signals,multiplexing of signals (for instance, diplexing or triplexing), or anysuitable combination thereof. The delay line 406 can be a DLL thatincludes any suitable combination of features of the DLLs disclosedherein.

In certain implementations, the mobile device 390 supports carrieraggregation, thereby providing flexibility to increase peak data rates.Carrier aggregation can be used for both Frequency Division Duplexing(FDD) and Time Division Duplexing (TDD), and may be used to aggregate aplurality of carriers or channels. Carrier aggregation includescontiguous aggregation, in which contiguous carriers within the sameoperating frequency band are aggregated. Carrier aggregation can also benon-contiguous, and can include carriers separated in frequency within acommon band or in different bands.

The antennas 394 can include antennas used for a wide variety of typesof communications. For example, the antennas 394 can include antennasfor transmitting and/or receiving signals associated with a wide varietyof frequencies and communications standards.

In certain implementations, the antennas 394 support MIMO communicationsand/or switched diversity communications. For example, MIMOcommunications use multiple antennas for communicating multiple datastreams over a single radio frequency channel. MIMO communicationsbenefit from higher signal to noise ratio, improved coding, and/orreduced signal interference due to spatial multiplexing differences ofthe radio environment. Switched diversity refers to communications inwhich a particular antenna is selected for operation at a particulartime. For example, a switch can be used to select a particular antennafrom a group of antennas based on a variety of factors, such as anobserved bit error rate and/or a signal strength indicator.

The mobile device 390 can operate with beamforming in certainimplementations. For example, the front end system 393 can includeamplifiers having controllable gain and phase shifters havingcontrollable phase to provide beam formation and directivity fortransmission and/or reception of signals using the antennas 394. Forexample, in the context of signal transmission, the amplitude and phasesof the transmit signals provided to the antennas 394 are controlled suchthat radiated signals from the antennas 394 combine using constructiveand destructive interference to generate an aggregate transmit signalexhibiting beam-like qualities with more signal strength propagating ina given direction. In the context of signal reception, the amplitude andphases are controlled such that more signal energy is received when thesignal is arriving to the antennas 394 from a particular direction. Incertain implementations, the antennas 394 include one or more arrays ofantenna elements to enhance beamforming.

The baseband system 391 is coupled to the user interface 397 tofacilitate processing of various user input and output (I/O), such asvoice and data. The baseband system 391 provides the transceiver 392with digital representations of transmit signals, which the transceiver392 processes to generate RF signals for transmission. The basebandsystem 391 also processes digital representations of received signalsprovided by the transceiver 392. As shown in FIG. 7 , the basebandsystem 391 is coupled to the memory 396 to facilitate operation of themobile device 390.

The memory 396 can be used for a wide variety of purposes, such asstoring data and/or instructions to facilitate the operation of themobile device 390 and/or to provide storage of user information.

The power management system 395 provides a number of power managementfunctions of the mobile device 390. In certain implementations, thepower management system 395 includes a PA supply control circuit thatcontrols the supply voltages of the power amplifiers 401. For example,the power management system 395 can be configured to change the supplyvoltage(s) provided to one or more of the power amplifiers 401 toimprove efficiency, such as power added efficiency (PAE).

As shown in FIG. 7 , the power management system 395 receives a batteryvoltage from the battery 398. The battery 398 can be any suitablebattery for use in the mobile device 390, including, for example, alithium-ion battery.

The 3rd Generation Partnership Project (3GPP) introduced Phase 1 offifth generation (5G) technology in Release 15, and is currently in theprocess of developing Phase 2 of 5G technology in Release 16. Subsequent3GPP releases will further evolve and expand 5G technology. 5Gtechnology is also referred to herein as 5G New Radio (NR).

5G NR supports or plans to support a variety of features, such ascommunications over millimeter wave spectrum, beamforming capability,high spectral efficiency waveforms, low latency communications, multipleradio numerology, and/or non-orthogonal multiple access (NOMA). Althoughsuch RF functionalities offer flexibility to networks and enhance userdata rates, supporting such features can pose a number of technicalchallenges.

The teachings herein are applicable to a wide variety of communicationsystems, including, but not limited to, communication systems usingadvanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro,and/or 5G NR. DLLs disclosed herein can be implemented in relativelyhigh frequency applications, for example, for modulating and/ordemodulating FM signals.

FIG. 8 is a schematic diagram of one example of a communication network100. The communication network 100 includes a macro cell base station 1,a mobile device 2, a small cell base station 3, and a stationarywireless device 4. Any device or components in the communication network100 can include a DLL in accordance with any suitable principles andadvantages disclosed herein.

The illustrated communication network 100 of FIG. 8 supportscommunications using a variety of technologies, including, for example,4G LTE, 5G NR, and wireless local area network (WLAN), such as Wi-Fi. Inthe communication network 100, dual connectivity can be implemented withconcurrent 4G LTE and 5G NR communication with the mobile device 2.Although various examples of supported communication technologies areshown, the communication network 100 can be adapted to support a widevariety of communication technologies.

Various communication links of the communication network 100 have beendepicted in FIG. 8 . The communication links can be duplexed in a widevariety of ways, including, for example, using frequency-divisionduplexing (FDD) and/or time-division duplexing (TDD). FDD is a type ofradio frequency communications that uses different frequencies fortransmitting and receiving signals. FDD can provide a number ofadvantages, such as high data rates and low latency. In contrast, TDD isa type of radio frequency communications that uses about the samefrequency for transmitting and receiving signals, and in which transmitand receive communications are switched in time. TDD can provide anumber of advantages, such as efficient use of spectrum and variableallocation of throughput between transmit and receive directions.

As shown in FIG. 8 , the mobile device 2 communicates with the macrocell base station 1 over a communication link that uses a combination of4G LTE and 5G NR technologies. The mobile device 2 also communicationswith the small cell base station 3. In the illustrated example, themobile device 2 and small cell base station 3 communicate over acommunication link that uses 5G NR, 4G LTE, and Wi-Fi technologies. Incertain implementations, enhanced license assisted access (eLAA) is usedto aggregate one or more licensed frequency carriers (for instance,licensed 4G LTE and/or 5G NR frequencies), with one or more unlicensedcarriers (for instance, unlicensed Wi-Fi frequencies).

In certain implementations, the mobile device 2 communicates with themacro cell base station 1 and the small cell base station 3 using 5G NRtechnology over one or more frequency bands that within Frequency Range1 (FR1) and/or over one or more frequency bands that are above FR1. Theone or more frequency bands within FR1 can be less than 6 GHz. Forexample, wireless communications can utilize FR1, Frequency Range 2(FR2), or a combination thereof. In one embodiment, the mobile device 2supports a HPUE power class specification.

The illustrated small cell base station 3 also communicates with astationary wireless device 4. The small cell base station 3 can be used,for example, to provide broadband service using 5G NR technology. Incertain implementations, the small cell base station 3 communicates withthe stationary wireless device 4 over one or more millimeter wavefrequency bands in the frequency range of 30 GHz to 300 GHz and/or uppercentimeter wave frequency bands in the frequency range of 24 GHz to 30GHz.

In certain implementations, the small cell base station 3 communicateswith the stationary wireless device 4 using beamforming. For example,beamforming can be used to focus signal strength to overcome pathlosses, such as high loss associated with communicating over millimeterwave frequencies.

The communication network 100 of FIG. 8 includes the macro cell basestation 1 and the small cell base station 3. In certain implementations,the small cell base station 3 can operate with relatively lower power,shorter range, and/or with fewer concurrent users relative to the macrocell base station 1. The small cell base station 3 can also be referredto as a femtocell, a picocell, or a microcell.

Although the communication network 100 is illustrated as including twobase stations, the communication network 100 can be implemented toinclude more or fewer base stations and/or base stations of other types.As shown in FIG. 8 , base stations can communicate with one anotherusing wireless communications to provide a wireless backhaul.Additionally or alternatively, base stations can communicate with oneanother using wired and/or optical links.

The communication network 100 of FIG. 8 is illustrated as including onemobile device and one stationary wireless device. The mobile device 2and the stationary wireless device 4 illustrate two examples of userdevices or user equipment (UE). Although the communication network 100is illustrated as including two user devices, the communication network100 can be used to communicate with more or fewer user devices and/oruser devices of other types. For example, user devices can includemobile phones, tablets, laptops, IoT devices, wearable electronics,and/or a wide variety of other communications devices.

User devices of the communication network 100 can share availablenetwork resources (for instance, available frequency spectrum) in a widevariety of ways.

In one example, frequency division multiple access (FDMA) is used todivide a frequency band into multiple frequency carriers. Additionally,one or more carriers are allocated to a particular user. Examples ofFDMA include, but are not limited to, single carrier FDMA (SC-FDMA) andorthogonal FDMA (OFDMA). OFDMA is a multicarrier technology thatsubdivides the available bandwidth into multiple mutually orthogonalnarrowband subcarriers, which can be separately assigned to differentusers.

Other examples of shared access include, but are not limited to, timedivision multiple access (TDMA) in which a user is allocated particulartime slots for using a frequency resource, code division multiple access(CDMA) in which a frequency resource is shared amongst different usersby assigning each user device a unique code, space-divisional multipleaccess (SDMA) in which beamforming is used to provide shared access byspatial division, and non-orthogonal multiple access (NOMA) in which thepower domain is used for multiple access. For example, NOMA can be usedto serve multiple user devices at the same frequency, time, and/or code,but with different power levels.

Enhanced mobile broadband (eMBB) refers to technology for growing systemcapacity of LTE networks. For example, eMBB can refer to communicationswith a peak data rate of at least 10 Gbps and a minimum of 100 Mbps foreach user device. Ultra-reliable low latency communications (uRLLC)refers to technology for communication with very low latency, forinstance, less than 2 milliseconds. uRLLC can be used formission-critical communications such as for autonomous driving and/orremote surgery applications. Massive machine-type communications (mMTC)refers to low cost and low data rate communications associated withwireless connections to everyday objects, such as those associated withInternet of Things (IoT) applications.

The communication network 100 of FIG. 8 can be used to support a widevariety of advanced communication features, including, but not limitedto eMBB, uRLLC, and/or mMTC.

A peak data rate of a communication link (for instance, between a basestation and a user device) depends on a variety of factors. For example,peak data rate can be affected by channel bandwidth, modulation order, anumber of component carriers, and/or a number of antennas used forcommunications.

For instance, in certain implementations, a data rate of a communicationlink can be about equal to M*B*log₂(1+S/N), where M is the number ofcommunication channels, B is the channel bandwidth, and S/N is thesignal-to-noise ratio (SNR).

Accordingly, data rate of a communication link can be increased byincreasing the number of communication channels (for instance,transmitting and receiving using multiple antennas), using widerbandwidth (for instance, by aggregating carriers), and/or improving SNR(for instance, by increasing transmit power and/or improving receiversensitivity).

5G NR communication systems can employ a wide variety of techniques forenhancing data rate and/or communication performance.

Any of the embodiments described above can be implemented in associationwith mobile devices such as cellular handsets. The principles andadvantages of the embodiments can be used for any systems or apparatus,such as any uplink wireless communication device, that could benefitfrom any of the embodiments described herein. The teachings herein areapplicable to a variety of systems. Although this disclosure includessome example embodiments, the teachings described herein can be appliedto a variety of structures. Any of the principles and advantagesdiscussed herein can be implemented in association with RF circuitsconfigured to process signals in a frequency range from about 30 kHz to300 GHz, such as in a frequency range from about 3 GHz to 20 GHz or in afrequency range from about 10 GHz to 60 GHz.

Aspects of this disclosure can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products such as packaged radio frequency modules, uplinkwireless communication devices, wireless communication infrastructure,electronic test equipment, etc. Examples of the electronic devices caninclude, but are not limited to, a mobile phone such as a smart phone, awearable computing device such as a smart watch or an ear piece, atelephone, a television, a computer monitor, a computer, a modem, ahand-held computer, a laptop computer, a tablet computer, a microwave, arefrigerator, a vehicular electronics system such as an automotiveelectronics system, a stereo system, a digital music player, a radio, acamera such as a digital camera, a portable memory chip, a washer, adryer, a washer/dryer, a copier, a facsimile machine, a scanner, amulti-functional peripheral device, a wrist watch, a clock, etc.Further, the electronic devices can include unfinished products.

Unless the context indicates otherwise, throughout the description andthe claims, the words “comprise,” “comprising,” “include,” “including”and the like are to generally be construed in an inclusive sense, asopposed to an exclusive or exhaustive sense; that is to say, in thesense of “including, but not limited to.” Conditional language usedherein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,”“for example,” “such as” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orstates. The word “coupled”, as generally used herein, refers to two ormore elements that may be either directly connected, or connected by wayof one or more intermediate elements. Likewise, the word “connected”, asgenerally used herein, refers to two or more elements that may be eitherdirectly connected, or connected by way of one or more intermediateelements. Additionally, the words “herein,” “above,” “below,” and wordsof similar import, when used in this application, shall refer to thisapplication as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel resonators described hereinmay be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the resonatorsdescribed herein may be made without departing from the spirit of thedisclosure. Any suitable combination of the elements and/or acts of thevarious embodiments described above can be combined to provide furtherembodiments. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the disclosure.

What is claimed is:
 1. A dispersive delay line comprising: apiezoelectric substrate including a first region, a second region, and athird region; a first interdigital transducer electrode on the firstregion of the piezoelectric substrate; a second interdigital transducerelectrode on the second region of the piezoelectric substrate; and anadditional material on the third region of the piezoelectric substrate,the additional material configured to adjust acoustic wave propagationvelocity in the third region of the piezoelectric substrate, thedispersive delay line arranged such that a Lamb wave of wavelength λ isconfigured to propagate from the first interdigital transducer electrodeto the second interdigital transducer electrode though the third regionof the piezoelectric substrate with a group delay that depends onfrequency.
 2. The dispersive delay line of claim 1 wherein theadditional material is positioned on both a top surface and a bottomsurface of the piezoelectric substrate in the third region.
 3. Thedispersive delay line of claim 1 wherein the additional materialincludes silicon dioxide.
 4. The dispersive delay line of claim 1wherein the additional material includes gallium nitride.
 5. Thedispersive delay line of claim 1 wherein the additional materialincludes silicon nitride.
 6. The dispersive delay line of claim 1wherein the piezoelectric substrate has a substantially constantthickness in the first region, the second region, and the third region.7. The dispersive delay line of claim 1 wherein the group delay has anon-linear relationship with frequency.
 8. The dispersive delay line ofclaim 1 wherein the group delay has a linear relationship withfrequency.
 9. The dispersive delay line of claim 1 wherein thedispersive delay line has a passband bandwidth in a range from 0.5gigahertz to 2 gigahertz.
 10. The dispersive delay line of claim 1wherein the dispersive delay line has a passband bandwidth of more than1 gigahertz.
 11. The dispersive delay line of claim 1 wherein the groupdelay is in a range from 20 nanoseconds to 100 nanoseconds.
 12. Thedispersive delay line of claim 1 wherein the dispersive delay line hasan operating frequency in range from 5 gigahertz to 10 gigahertz. 13.The dispersive delay line of claim 1 wherein the dispersive delay linehas an operating frequency in Frequency Range 2 defined by a New Radiostandard.
 14. The dispersive delay line of claim 1 wherein thepiezoelectric substrate includes aluminum nitride.
 15. The dispersivedelay line of claim 14 wherein the Lamb wave is a lowest order symmetricmode Lamb wave.
 16. The dispersive delay line of claim 1 wherein theLamb wave is a lowest order symmetric mode Lamb wave.
 17. A radiofrequency module comprising: a dispersive delay line including apiezoelectric substrate, a first interdigital transducer electrode on afirst region of the piezoelectric substrate, a second interdigitaltransducer electrode on a second region of the piezoelectric substrate,and an additional material on a third region of the piezoelectricsubstrate, the additional material configured to adjust acoustic wavepropagation velocity in the third region of the piezoelectric substrate,the dispersive delay line arranged such that a Lamb wave of wavelength λis configured to propagate from the first interdigital transducerelectrode to the second interdigital transducer electrode though thethird region of the piezoelectric substrate with a group delay thatdepends on frequency; a radio frequency circuitry coupled to thedispersive delay line; and packaging structure enclosing the dispersivedelay line and the radio frequency circuitry.
 18. The radio frequencymodule of claim 17 wherein the radio frequency circuitry includes aradio frequency amplifier.
 19. A wireless communication devicecomprising: a dispersive delay line including a piezoelectric substrate,a first interdigital transducer electrode on a first region of thepiezoelectric substrate, a second interdigital transducer electrode on asecond region of the piezoelectric substrate, and an additional materialon a third region of the piezoelectric substrate, the additionalmaterial configured to adjust acoustic wave propagation velocity in thethird region of the piezoelectric substrate, the dispersive delay linearranged such that a Lamb wave of wavelength λ is configured topropagate from the first interdigital transducer electrode to the secondinterdigital transducer electrode though the third region of thepiezoelectric substrate with a group delay that depends on frequency;and an antenna in communication with the dispersive delay line.
 20. Thewireless communication device of claim 19 wherein the wirelesscommunication device is a mobile phone.